The present invention relates to lighting systems and in particular to an improved lighting system for lighting a work area with reduced glare and veiling reflections.
In U.S. Pat. No. 4,054,793 issued Oct. 18, 1977 to Sylvan R. Shemitz there is disclosed a desk level work area lighting system. As set forth in that patent, the object of such systems is to provide lighting whereby direct glare and veiling reflections are substantially eliminated from a task positioned at the work area. For this reason such lighting systems are commonly referred to as "task" lighting. The Shemitz patent utilizes a light fixture positioned above the desk. Light from a linear source(i.e., such as an elongated fluorescent tube) is reflected through a refractor member having prisms extending perpendicular to the light source. The resultant distribution of luminous flux from the Shemitz system is illustrated in FIG. 3 of that patent which, for convenience, is reproduced as FIG. 1 of the present application. In order to reduce direct glare and veiling reflections on the desk top surface, the half bat wing configuration of luminous flux eminating from the fixture is directed to the right and left by the refractor member shown in FIG. 1.
The sacrifice paid for eliminating glare and veiling reflections from the center of the work area is decreased illumination at the extremes of the desk. That is, when a person is sitting at the center of the desk and looks to his right or left, those areas will appear abnormally dark. An actual measurement of foot candle distribution over the desk top surface (taken with a Weston Foot Candle meter, Model 756 which was visual and cosine corrected) for a lighting system utilizing the refractor of the Shemitz patent is set forth in FIG. 2. As can be seen, the available foot candles of light drops off drastically at the right and left ends of the desk as compared with the center of the desk and in fact are less than 60% of the foot candles available at the center of the desk. Thus, a worker whose work is spread over the entire desk would have difficulty seeing and working on a task positioned at the ends of his desk.
In view of the above, it is the principal object of the present invention to provide an improved lighting system for a desk level work station capable of providing reduced direct glare and veiling reflections to the work station, while providing substantially uniform light distribution over the entire work station.
A further object is to provide such a system which is sufficiently flexible to permit the light flux distribution to be varied as required over the desk top.
Further objects and advantages will become evident from the following Specification.